1. Field of the Invention
The present invention relates to an apparatus for holding guide vanes such as bowed turning vanes in a duct, and a method for assembly of such vanes onto support rails therefor.
2. Description of the Prior Art
Turning vanes are used to direct moving gases around duct corners where the ends of two ducts positioned at right angles intersect, such as heating or ventilation air ducts. If vanes are not used, air strikes the wall of the intersecting duct. This can cause turbulence or backflow in the duct. The vanes are positioned diagonally across the duct corner region to guide the air flow smoothly around the corner.
A commonly used turning vane is constructed by joining two pieces of curved sheet metal, having different radii of curvature, at their edges. This results in a hollow vane, with a crescent-shaped cross section. A single sheet of curved sheet metal has also been used as a vane, having only a single thickness in bowed cross section. Such vanes, whether of single or double wall construction, can be cut to whatever length is needed in a duct.
Positioning and fastening of vanes in an assembly which permits proper positioning in a duct has been an expensive and labor-intensive process. Many techniques for fastening vanes to a pair of opposed parallel sheet metal rails or to the ducts themselves have been tried. For the most part, these techniques have been unsatisfactory because they involve special fasteners, additional labor-intensive steps or expensive tooling on the sheet metal. Fastening techniques using special fasteners are unsuitable because such fasteners are quite expensive in relation to the cost of the end product. Relative labor costs also become expensive when extra labor-intensive activities are required to fasten a vane to a rail.
The present invention fulfills the need for a duct vane mounting assembly method and apparatus which does not require special fasteners, which can be inexpensively produced and which requires minimal labor for the attachment of the turning vanes to a support rail or rails.